Power semiconductor devices such as Insulated-Gate Bipolar Transistors (IGBT) have found use in a wide range of applications, for example as building blocks in power converters for high voltage applications.
An example of an IGBT power module is shown in US 2014/0319669 A1, which discloses a power module that includes a power semiconductor chip. The power module further includes a case that accommodates the power semiconductor chip. A silicone gel seals the power semiconductor chip within the case.
In recent years, there has been a growing interest in installing electrical installations on the sea floor in depths from a few tens of meters to even kilometers. Oil and gas production subsea employs electric equipment like drilling motors, pumps, and compressors driven by frequency converters.
In bringing power electronics subsea, two general concepts exist: (1) the equipment stays at or near atmospheric pressure in a pressure vessel; and (2) the equipment is pressurized to the hydrostatic pressure level on sea ground which can be several hundreds of bar. The two concepts can be differentiated as follows. Concept (1) has the advantage that standard electric/electronic components, known from onshore installations, can be used, while disadvantages include thick walls needed for the enclosure to withstand the pressure difference between inside and outside. Thick walls make the equipment heavy and costly. Concept (2) has the advantage that no thick walls are needed for the enclosure since the pressure difference between inside and outside the containment is much less than for concept (1).
A subsea module of concept type (2) is filled with a dielectric liquid such as oil, to counteract deformation of the subsea module enclosure and to provide adequate electrical insulation between electrical components contained in the subsea module.